Looper mechanism for sewing machines



1 May 27, 1947.

L. .M. BALLAMY ET AL 1,179

LOOPER MECHANISM FOR SEWING MACHINES Filed Oct. 7, 1943 2 Sheets-Sheet lay 27, 1947. L. M. BALLAMY ET AL 5 79 LOOI ER MECHANISM FOR SEWINGMACHINES Filed Oct. '7, 1943 2 Sheets-Sheet 2 Patented May 27, 1947LOOPER MECHANISM FOR SEWING MACHINES Leslie Mark Ballamy, Caterham, andRichard. Hasell Sheepshanks', Eyke, Wooclbridge, England ApplicationOctober 7, 1943, Serial' No. 505,372 in Great Britain ()ctober 23, 19427 Claims.

This invention relates to looper mechanism for sewing machines and ithas for its primary object to provide an improved form and constructionof looper'mechanism which is exceptionally Simple to manufacture and isnevertheless reliable in operation.

In particular the invention is concerned with sewing machines of theform described in the specification of United- States of America PatentNo. 1,622,774 which produces a form of chain stitch by employing upperand lower threads, both ofwhich are-fed directly from kops or other bulksupplies.

In the sewing machine described-in the abovementioned specification aneedle mounted in a reciprocating needle bar serves tocarry the upperthread and pass it in andiout of the material to besewnLtheloopercomprises a member disposed below the usualthroatplate of the sewingmachineand. having a nose portion which is perforated to carry thelowerthread-driving mechanism comprising. cranks and sliders being arrangedto move the nose of the looper so that its executes a somewhatelliptical path around theaxis of reciprocation of. the needle, therebypassing thelower thread throughrthe loop which is.formed by theupperthreadduring eachpene- ,trat-ionand retraction of the needle.

It-is a further object of the invention-to simplify-this-mechanismand toprovide an arrangementin which the'nu'mber of parts requiringlubrication is considerably reduced; also in the improved arrangementthefrictional resistance is verymuchless than in thepreviousconstructions, thus enabling. the sewing. machine to be driven with.less power.

In accordance with the invention looper mechanism. is provided for asewing machine, said looper mechanism comprising an angularly movablearmcarrying a-looper member, and a cam member which oscillates said armin two mutually perpendicular planes.

There istfurther provided according to the. inventionlooper mechanismfor a sewing machine comprisinganarm for manipulating the loopermembenandarotatable cam formed with a cam track, which latter is engagedbyla follower connectedwith the arm, said track serving to move thefollower radially with respect to the axis of camlrotation, .and also ina lateral direction.hav ing a component parallel with saidaxis, both ofsaid .movements taking place during eachoper- .ating cycle .ofthemechanism.

Conveniently the cam is formed with aperipheral groove which constitutesa cam track and 2 is engaged by a follower comprising a projectioncarried by the arm. The bottom of the groove may position the followerin the radial direction, and at least one side of the groove-positionsthe follower laterally. Further, the follower may comprise a head upon ascrew-threaded stem, which latter is fitted adjustably in the arman'diis provided with locking means, said stem serving to regulate theposition of the looper member for any given position of-the cam. Inthe'preferred construction the arm is pivotally mounted by means of avrubber or like flexible sleeve arranged to allow angular movement of thearm in a plane containing the axis of the sleeve, the material of thesleeve conveniently acting in torsion to allow angular movement of thearm about the axis ofthe sleeve. Where the axis of the'sleeve issubstantially parallel withthe axis of rotation of the'cam, the sleevemay be stressed'in torsion when the mechanism is assembled, thus urgingthe follower resiliently into engagement withthe cam; A looper membermay be carried by that end of the arm opposite to the pivotal mountingof'said arm, the follower being disposed substantially midway betweenthe axis of pivotal mounting and'the looper member.

The invention is illustrated by way of example in the accompanyingdiagrammatic drawings, in which:

Figure 1 is an elevation of a looper mechanism as applied to a machineadapted to produce a plurality of rows of stitching simultaneously;

Figure 2 is anend elevation of the mechanism shown in Figure 1;

Figure 3 is afragmentary sectional elevation of the pivotal mounting ofthe looper arm drawn to an enlarged scale;

Figure 4 is a fragmentary plan of a modified form ofcam and followerdevice; and

Figure 5 is an elevation showinga convenient arrangement for use where aplurality of'looper mechanisms are required to operate simultaneollslybut with different phases.

Inthe arrangementshown in Figures 1 and 2 a-transverse table I0 isincorporated in the framework of the sewing machine and is formed in itsupper surface with a longitudinal groove ll serving to locate a numberofbearing brackets, two of which are indicated at I2 and I3. The bracketsl2 and it are securely clamped to the table Ill by bolts l4, and theycarry a rotatable camshaft l5 arranged to be-continuously rotatedconveniently through a toothed-clutch l6 of the ratchet type; the shaft15 ismounted in the brackets l2 and [3 by ball or roller bearings (notshown) and carries a cam, which is indicated at I! and will behereinafter described in detail. Also secured to the table I is abracket iii of substantially U shape secured by a bolt I9 and located bya rectangular' projection 20 engaging within a groove 2! formed in thetable. The bracket l8 serves as a pivotal mounting for a looper arm 22,which is substantially semi-circular in shape, as will be seen in Figure2, and extends upwardly around the cam ll. The top of the looper arm 22is fitted with a. transverse bar 23, which is conveniently secured byscrews 24 and is drilled for the accommodation of a plurality of loopermembers 25 of the usual form, these being held in position each by apair of grub screws 25. The looper members 25 co-operate withcorresponding machine needles, one of which is indicated in broken linesat 21 in Figure 2, and said looper members are required to move aroundthe needle axes by following an elongated orbit of approximately ovalshape, said orbit being completed once for each cycle of movement of themachine needle 21.

In order that the desired movement of the looper arm 22 may be efiectedin an extremely simple manner with very few moving parts, said arm isarranged to be oscillated in the plane of Figure 1 and simultaneously inthe plane of Figure 2, both movements being effected by the cam IT. Forthis purpose the cam I1 is of substantially cylindrical form but ismounted eccentrically upon the shaft 15, as will be seen clearly inFigure 2. It is formed in its periphery with a groove 28, which, inradial section, is of substantially uniform depth and is somewhatsemicircular in shape. This groove is engaged by a somewhathemi-spherical head 29 fitted to a stem 30, which latter isscrew-threaded into the looper arm 22 and is provided upon itsprojecting end 3| with a lock nut 32. A transverse slot 33 enables thestem 30 to be rotated and the position of the arm 22 relative to thehead 29 to be adjusted finely thereby. The looper arm 22 is urgedresiliently in a direction towards the cam 11 by means incorporated inthe pivotal mounting of the arm, as will be hereinafter explained, andit will be seen, therefore, that the eccentric disposition of the groove28 in the cam I1 brings about the main oscillation of the looper arm 22in the plane of Figure 2. In order to bring about the simultaneousoscillation in the plane of Figure l the groove 28 undulates in an axialdirection, as will be clear from Figure 1, in which the part of thegroove 28 in the front of the cam is displaced to the left and theportion of the groove in the rear part of the cam is displaced to theright. The side walls 34 and 35, between which the head 29 fits snugly,are, of course, parallel with one another, and they may lie in planeswhich are disposed at the requisite inclination to the plane normal tothe axis of the cam. It will be seen by comparison of Figures 1 and 2that the positions of maximum axial deviation, indicated at 36 and 31,lie approximately upon the diameter 38 extending at right angles to thediameter 39 containing the axis of the shaft 15. As the followerconstituted by the head 29 is disposed between the fulcrum at the lowerend of the looper arm 22 and the looper members 25 at the upper end ofthe arm 22, it follows in practice that very little axial deviation orundulation of the groove 28 is required in order to make the loopermembers 25 pass around their respective needle axes for producing theusual stitching action.

The construction of the preferred form of pivotal mounting for thelooper arm 22 is shown in Figure 3. The lower part of the arm 22 isprovided with an integral tubular portion 40, which is split andprovided with a tightening bolt 4! (see Figure 2) in order that it maybe clamped around a resilient bearing unit indicated at 42. This bearingunit comprises an outer metal sleeve 43 and an inner sleeve 44, betweenwhich is disposed an annular bush 45 of soft resilient rubber or likematerial. The bush 45 is in a state of compression and/or is fastened tothe sleeves 43 and 44, so that relative angular movement of the sleevesusually takes place by creating torsional stress in the bush 45. Thesleeve 44 is secured by a bolt 46 passing through the limbs Isa and 18bof the bracket l8, said sleeve 44 being slightly longer than the sleeve43, thus allowing it to be clamped firmly within the bracket l8 withouthampering the movements of the looper arm 22. Owing to the provision ofthe resilient bush 45 the looper arm- 22 can move angularly about theaxis of the bolt 46 (i. e., in the plane of Figure 2), and it can alsooscillate sideways (i. e., in the plane of Figures 1 and 3). Further, byappropriately adjusting the arm 22 angularly around the sleeve 43 beforetightening the bolt 4|, the resilience of the bush 45 is utilised tourge said looper arm 22 so that the head 29 is maintained in firmengagement with the cam ll; for instance, the desired adjustment can beobtained and the bolts 4| and 46 tightened while the bracket l8 and thelooper arm 22 are removed from the table H].

In the modified form of device shown in Figure 4 the cam I7 is againsubstantially cylindrical in form and is mounted eccentrically upon theshaft !5. Its periphery, however, is formed with a circumferential ribor flange 41, which undulates in an axial sense and is engaged by aslotted cylindrical block 48 mounted within a head 29a formed upon thescrew-threaded stem 30. The block 48 is thus free through anyconventional mounting to move angularly about the axis of the stem 30and to accommodate itself to the varying inclinations of the rib orflange 41. As will be clear from Figure 4, this rib or flange 41 doesnot lie in a single inclined plane, but is constituted by two portions49 and 50 which lie in mutually parallel radial planes and are joined byrelatively steep portions 5| and 52 arranged to move the looper members25 at a rapid rate from one side of the needle axis to the other, suchmovement, of course, taking place in the plane of Figure 1. If desiredthe groove 28 of Figure 1 may be shaped in a similar manner.

Figure 5 shows a convenient arrangement which can be adopted where anumber of looper arms 22a, 22b, 22c and 22d are disposed side by sideand are required to be operated by a corresponding number of coaxialcams Ha, 1 lb, I10 and lld. Although the looper members 25 form anequidistantly spaced continuous series, the looper arms 22a etc. arearranged in pairs, each pair having between them a bearing bracket forsupporting a common camshaft I5. Thus the bearing bracket between thearms 22a and 22b is indicated at 13a, while the one between the looperarms 22c and 22d is indicated at 13?). This enables the camshaft 15 tobe rigidly supported adjacent each cam and at the same time requiresonly a small number of bearing brackets.

It will be understood that the constructions which have been describedare given merely by way of example and that various modifications arepossible.

What we claim is:

1. Looper mechanism for a sewing machine comprising a cam rotatableabout an axis and having follower engaging surfaces for actuating thefollower radially and axially of the cam, a looper supporting arm havinga follower engagin said cam, and a resilient mounting for one end ofsaid arm yieldably urging the follower into contact with the cam andpermitting movement of the arm both radially and axially of the camthrough corresponding movement of the follower.

2. A construction as defined in claim 1, wherein said follower comprisesa head carried by one end of a stem having an adjustable threadedcooperation with the arm.

3. A construction as defined in claim 1, wherein the resilient mountingfor the arm includes a metallic sleeve on which the arm is adjustablysupported, and a resilient rubber bushing directly supporting the sleeveand held under compression by said sleeve.

4. A construction as defined in claim 1, wherein the arm' is curved inthe form of an arc embracing the cam and extending partly around thecircumference of the cam with the respective ends of the arms lying in aplane including the axis of the cam.

5. A looper mechanism for a sewing machine, comprising a continuouslyrotatable cam shaft, a cam mounted thereon and having a circumferentialgroove forming a cam track with mutually parallel side walls, an arm, auniversal mounting for one end of the arm, a looper member carried bythe other end of the arm, a cam follower projection carried by the armbetween the universal mounting and the looper member and engaging theside walls of the cam track, said universal mounting including aresilient means urging the arm to hold the follower projection withinthe cam track, said cam track being eccentric with respect to the axisof the cam shaft and shaped to deviate axially from the trulycircumferential direction whereby each turn of the cam moves the camfollower and the arm in two mutually perpendicular planes.

6. Looper mechanism for a sewing machine, including a cam memberrotatable about an axis and having follower engaging surfaces foractuating the follower radially and axially of the cam memher, anangularly movable arm having a follower engaging said cam, a mounting atone end of the arm yieldably urging the follower into contact with thecam and permitting movement of the arm both radially and axially of thecam, and a looper member carried by the opposite end of the arm, the cammember cooperating with the arm at a point in the arm closer to themounting than to the looper member.

'1. A construction as defined in claim 6, wherein said follower issupported by a stem adjustably engaged with the arm for adjustment ofthe follower radially of the cam.

LESLIE MARK BALLAMY. RICHARD HASELL SHEEPSHANKS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 946,064 Merrick Jan. 11, 19101,123,579 Onderdonk 1. Jan. 5, 1915 1,127,755 Gray Feb. 9, 1915

